Question

Given an integer n, return true if it is a power of two. Otherwise, return false.

An integer n is a power of two, if there exists an integer x such that n == 2x.

Example 1:

Input: n = 1
Output: true
Explanation: 20 = 1

Example 2:

Input: n = 16
Output: true
Explanation: 24 = 16

Example 3:

Input: n = 3
Output: false

Constraints:

  • -231 <= n <= 231 - 1

Solution

Time Complexity O(log n)

Space Complexity O(log n)

Time Complexity O(log n)

Space Complexity O(1)

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Question

Implement pow(x, n), which calculates x raised to the power n (i.e., xn).

Example 1:

Input: x = 2.00000, n = 10
Output: 1024.00000

Example 2:

Input: x = 2.10000, n = 3
Output: 9.26100

Example 3:

Input: x = 2.00000, n = -2
Output: 0.25000
Explanation: 2-2 = 1/22 = 1/4 = 0.25

Constraints:

  • -100.0 < x < 100.0
  • -231 <= n <= 231-1
  • -104 <= xn <= 104

Solution

Time Complexity O(n)

Space Complexity O(1)

Time Complexity O(log n)

Space Complexity O(log n)

Time Complexity O(log n)

Space Complexity O(1)

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Question

Given an integer array nums, return all the triplets [nums[i], nums[j], nums[k]] such that i != j, i != k, and j != k, and nums[i] + nums[j] + nums[k] == 0.

Notice that the solution set must not contain duplicate triplets.

Example 1:

Input: nums = [-1,0,1,2,-1,-4]
Output: [[-1,-1,2],[-1,0,1]]

Example 2:

Input: nums = []
Output: []

Example 3:

Input: nums = [0]
Output: []

Constraints:

  • 0 <= nums.length <= 3000
  • -105 <= nums[i] <= 105

Solution

Time Complexity O(nยณ)

Space Complexity O(d) where d is the number of possible sets

Time Complexity O(nยฒ)

Space Complexity O(n + d) where d is the number of possible sets

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